Scotland benefits from every pound of the UK’s £34 billion annual defence
budget and not just the money spent directly north of the Border, according
to a report being unveiled by Philip Hammond warning the same protection
could not be provided after independence.

Philip Hammond will tomorrow unveil an analysis of how Scotland benefits from the UK's defence spendingPhoto: OLI SCARFF/GETTY IMAGES

The Defence Secretary will tomorrow unveil an 86-page analysis explaining how Scotland is defended by the three armed forces and cyber and intelligence services as part of an “integrated” system that stretches across the UK.

Highlighting how difficult it would be to unpick this, the civil service report warns Alex Salmond he may be faced with forming a separate defence force from scratch as he could not “co-opt” Scottish servicemen currently serving in the British armed forces.

The manning of a Scottish army, navy and air force is of “acute significance”, the study will state, as all three would be required immediately after independence but the UK’s Scottish personnel are “unlikely” to want to leave to join a smaller force.

It is also expected to raise questions over how a separate Scotland could afford to maintain existing bases, purchase the required aircraft and sea vessels and create new command and control structures “with a smaller tax base”.

The Scottish Nationalists have promised to spend £2.5 billion a year on defence after independence, which they said is £500 million more than is currently physically spent north of the Border.

But the report will argue this fails to take into account any of the manpower and equipment in the rest of the UK, and abroad, that currently helps keep Scotland safe.

Although a separate Scotland would be due a share of the UK’s defence assets, the report predicted the negotiations would be “difficult” and especially so over the question of personnel and citizenship.

“An independent Scottish state would face a very significant challenge to establish, man and equip its armed forces and wider defence and security structures,” the study will state.

“With a smaller tax base, an independent Scottish state would have to consider seriously its ability to sustain levels of investment at existing bases, particularly where these are currently geared towards support for specific, high-end capabilities.”

The study will cite the expense of RAF Lossiemouth, which is currently home to three squadrons of Tornado jets and will in future home three squadrons of Typhoons.

“It is not clear” whether a separate Scotland could afford such assets in the long term, the report will state, potentially having “a knock-on impact on local communities” near military bases.

But it will argue the UK has defence capabilities “of a scale and significance enjoyed by few other countries”, including aircraft carriers and destroyers, that allows it to conduct military and humanitarian operations simultaneously.

The report will also repeat doubts about the compatibility of the SNP’s pledge to restore the Scottish regiments and have 15,000 regular personnel, with two-thirds of the total expected to be swallowed up by support staff, leaving a combat force of only 4,650.

Keith Brown, the SNP’s Veterans Minister, said: “An independent Scotland will have first-class conventional forces which will play a full role in defending the country and cooperating with international partners – but we will not waste billions of pounds on Trident nuclear weapons or take part in illegal invasions like Iraq.”